The Bluetooth standard of communication allows devices to communicate wirelessly and achieve data transfer rates of up to 720 kilobytes per second. Bluetooth allows for a single digital wireless protocol that allows for synchronization and communication between multiple devices. Each time you connect your mobile device to a Bluetooth-enabled headset, car console, home phone or computer, a specific series of actions takes place in each communication.
When any two devices attempt to communicate, they must first agree on several points. Will they talk over wired or wireless signals? If over wire, how many wires? If wireless, on what frequency? Once the physical element is decided, a standard must then be established to determine how much data is sent at a time and how the devices will interpret data submitted and received. Bluetooth establishes a set of commands and responses that make up its communication protocol. This protocol dictates the range of transmissions, instructions to communicate, data packet segmentation and reassembly, connection setups, signal transfers and master-slave relationships.
Creating a connection between two Bluetooth-enabled devices requires a one-time manual connection. After turning on both devices, the master device -- typically a mobile phone -- will detect any active slave accessories it can connect to, like headsets. Connecting to a Bluetooth-enabled headset requires you to enter a multi-digit code to establish a relationship. Once the manual connection is established, the two devices will automatically establish conversations each time they are in range of one another. Provided the Bluetooth-enabled device is on, it will always be sending out signals searching for these connected devices to communicate with. That way, when you enter range of any previously-connected devices, the master and slave automatically connect and interact.
Bluetooth operates at a radio frequency of 2.45 gigahertz, a standard set by international agreement. Other devices like baby monitors and garage door openers likewise use this frequency, but Bluetooth is specially designed to not interfere or receive interference with other devices. It accomplishes this by its ability to send out incredibly weak signals of around one milliwatt. In contrast, standard mobile devices can transmit signals of up to three milliwatts. The low power of Bluetooth devices limits its range to 30 feet, severely reducing the chance of any noticeable interference with other electronics. Line of sight between devices isn't needed and it can transmit through walls with relative ease.
When Bluetooth-enabled devices come within range of each other, a wireless conversation takes place to determine if they have data to share. All of this is done without the user needing to push any buttons or give commands. Once a connection is established between two devices, they will always communicate with one another automatically. When a device is detected within range, the two Bluetooth systems create a personal-area network, also called a piconet. This PAN encompasses the distance between devices, whether it's from the mobile device in your pocket to the headset on your ear or to your car's Bluetooth console. Once the piconet is established, the devices regularly transmit data and intermittently change frequencies in unison to ensure they maintain contact while avoiding interfering with other piconets in the same proximity.
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